HI, I'm new. Thought I would drop in because I can post pictures here and felt like sharing my weekend project. Have an image first. More pics and words below...

Was looking for a cheap way to supplement my Fluval FX6, 406 and Marineland 220 in my dual aquarium setup and after some Googling and Youtubing, I decided on this wet/dry sump filter and siphon rig. It uses a simple storage container and 3 drawer organizer, about $18 total. Unlike store bought canister filters and most submersible filters, this wet/dry sump allows air to feed the bio media rather than the just oxygen in the water. There are a bunch of guides that better explain the benefits of sumps and the types and what not.

Let me break it down and start with the siphon overflow rig.

For those unfamiliar with how this siphon sump works, it's literally just using an airtight siphon to let gravity feed the Wet/Dry filter. The intake, as well as the filter's return, are kept near the surface so if the pump fails only about 10 gals or so from the top are siphoned off. The airline is tapped into the top of the main siphon loop going over the edge of the aquarium. It's important to make sure the feed to the filter, the 'T' connector, is above the bottom of the loop. Going up from the T is a vent for air. I got this rig idea from a bunch of places online with one change bending the vent pipe back over the aquarium to help it hang better on the aquarium and be better secured against heavy turtle bodies banging into it.

Also, this is designed so that if power goes out, once the power comes back on no priming or restarting of the overflow is needed since it doesn't lose it's siphon.

So one of my wife's master degrees is in environmental health and safety and she pointed out that PVC isn't all that great for drinking water nor water that you (turtles) live in. This was a bummer since the cheapest DIY siphon rigs that don't require drilling a tank or an expensive overflow box, use a PVC pipe system. After a bit of research, I settled on the much safer CPVC which is not only rated to handle hot water but supposedly doesn't leech its chemicals into the water over time. CPVC is noticeably (in person) shaded yellow compared to the white PVC along with all CPVC attachments. There was a negligible difference in price and I spent about $22 in these parts.

On the top of the main siphon loop I eventually drilled a hole to put in an air check valve but none of the glue I had would take hold of the valve's cheap plastic so I settle for just shoving a little airline in it instead and using some light activated epoxy and hotglue to make sure it was stuck and airtight. I used a bit of leftover plastic from the filter body to make a grate for the intake. I wasted $3 on the valve and $6 on the hose.

When I first was testing it, while it was working great, It would every 15 seconds or so much an unbearable sucking sound from the air vent. I ended up plugging the end of it and drilling a small hole in it to restrict the airflow while still allowing it to breathe. In the picture I have my temporary end cap I made with a scrap and hotglue to dial in the size of the hole. Some guides state this pipe should end below the main siphon tube/edge of the aquarium while others say it needs to end above.

If I could redo something I would rotate my intake 90 so that it didn't stick into the aquarium as far.

Here's my return from the filter. I reused a return I got from an old canister filter and added a piece of hose on the end to get it to the water level. It sticks up about 2 mm from the water so if the pump shuts off it sucks air instead of siphoning water.

So the water is dumped unceremoniously in the top drawer of the filter. This one has some mechanical filtration, cheap polyfil for quilts I got from Wal-mart for about $6. I added a plastic lid to help defuse the stream across more of the filter. This sump isn't really about mechanical filtration. I let my Fluval canisters handle that. This guy is all about biological filtration...

So the trick to any bio media is surface area and though 6 for $1 pot scrubbers are recommended by other sump DIYers I prefer luffas. $1 each almost anywhere they were much easier to find in the quantities I needed, take up the same space as 6 pot scrubbers, and arguably have more surface area. Also, a Dollar store may only have 6 packages of pot scrubbers on the shelf while a Walmart, Costco, or even HEB will have a big bin of luffas. If you're feeling weird you can get the ones with Paw Patrol on them. The 2nd drawer has 24 luffas while the 3rd drawer has 14 luffas and 60 pot scrubbers. This came out to about $48 total and was the most expensive component.

I used some eggcrate/light diffusor as a guide and drilled a bunch of holes in the bottom of each and tested with the pump to make sure the flow rate was good. Only about 1cm of water stays in each drawer. I drilled extra holes in the sides in case some bottom ones got clogged.

I decided to keep the lid on the base container and set the drawers on top to help reduce the evaporation since turtles like their warm water. I cut a hole in the top of the lid while leaving the formed bracing and screwed the drawers to it. I attempted to do a bit of caulking but the plastic was too flimsy in a few places. It worked out though because water leeks done the front and sides of the drawers and it weight bows the lid in to create a runoff back into circulation.

Holes cut for power and return hose.

I ended up purchasing a rate-adjustable 500gph fountain pump for $46 just a tad cheaper than the bio media. There are other options but I was a bit impatient to get this done over the weekend and looked like the best bang for my buck for something off the shelf.

One of the pros of this design is it gives a safe space for my heaters. My turtles love destroying heaters so anything to keep them away from them is great. You can kinda see one there in front.

I marked a running at 100% and a full off, aquarium siphoned off levels on my tank so I can notice any changes. One of the other benefits is any water loss from evaporation (or splash because RES's can only belly flop apparently) is reflected in the sump and not the aquarium. There's a guy on youtube who has a second contaier that uses a float valve to top off his sump when it gets low. I think that's future step for me as well.

This is Elegans and she's mean.

Moving forward I will try to make it a bit quieter as the water falling from drawer 3 to the container is a bit noisy. I also want to look into using a float switch to cut power to the pump to prevent a burn up if there's no water. I also plan to use an arduino or such to detect a water leak, release an air valve, and fire an airpump to blow air into the overflow to break the siphon and hopefully prevent additional leakage. Also, it's not exactly pretty so I may see about reworking my piping to come out the backside and giving the whole thing a black coating.

Welcome to the forum! Very interesting design, pretty ingenious. I have not heard of CPVC, I will look into it. Did your wife have any thoughts about the organizer and tote? A wireless leak detector would be an awesome side project too.